This disclosure relates to a high-resolution lithography process that uses a diffuse beam of electrons.
Current lithographic processes at the nanometer scale are limited by throughput and resolution. High-throughput techniques typically have lower resolutions, while high resolutions are only achievable through processes that are too slow for volume manufacture. Available photolithographic processes include deep ultraviolet (UV) and ultra-deep UV. Deep UV processes can achieve resolutions of 150 nanometers (nm) and have processing times on the order of tens of seconds per wafer. Ultra-deep UV processes, also referred to as extreme UV, achieve higher resolutions, on the order of tens of nanometers, but have processing times on the order of minutes per wafer. In addition, the smallest feature size in extreme UV is achieved using diffraction effects, so only simple patterns are possible.
Electron beam (e-beam) lithography can produce feature sizes lower than ten nanometers, and can accurately produce complex patterns. However, current e-beam techniques draw patterns on wafers by scanning a focused electron beam over the laser. This process can take hours per wafer, so it is not suitable for volume production. Microcontact printing can also achieve very high resolutions on the order of nanometers, and is also very fast, on the order of tens of seconds per wafer. However, microcontact printing has technical disadvantages that make it unsuitable for some semiconductor applications. For example, microcontract printing leaves a residue, the removal of which damages p-type gallium nitride, and microcontact printing cannot accommodate surfaces that are not flat.